| The acetylcholinesterase biosensors are applied to detect organophosphorus pesticides widely. The acetylcholinesterase can catalyze the substance to hydrolyzed selectively. And the activity of acetylcholinesterase can be restrained by the organophosphorus pesticides. We make use of the characteristic to design the biosensors to detect the content of organophosphorus pesticides. In order to improve the sensitivity of the biosensor, the electrochemical catalyst usually be used in the preparation of the biosensor. In this paper, we synthesized phthalocyanatocobalt(Ⅱ) (CoPc)and the 4,4′,4′′,4′′′-tetranitrophthalocyanatocobalt(Ⅱ)(CoTAPc). The molecular structure of the metal phthalocyanine derivatives were characterized by element analysis, FT-IR and UV/V. The 4,4′,4′′,4′′′-tetranitrophthalocyanatocobalt(Ⅱ) monomer was electropolymerized at a glassy carbon electrode(p-CoTAPc/GC) for detect cysteine. The electrode exhibited good electrocatalytic properties toward cysteine. An amperometric biosensor which introduced p-CoTAPc/GC for the detection of organophosphorus pesticides is described. Acetylcholinesterase was immobilized on a cellulose acetate membrane by cross-linking method. The enzyme membrane was then fixed on the surface of the polymeric cobalt(Ⅱ) tetraaminophthalocyanine (p-CoTAPc) film chemically modified electrode. The biosensor exhibited a linear response to acetylthiocholine in the concentration range of 5.0 ×10-2 to 1.2 mmol/L (γ=0.993). Following an incubation time of 10 min, the inhibition plots of percent inhibition versus the logarithm of parathion or dimethoate concentration were linear over the range of 1.0 ×10-9 to 1.0 ×10-6 mol/L, with a little variation between the two tested pesticides. The detection limits, calculated at 10%, are 7.0 ×10-10mol/L and 2.6 ×10-10 mol/L for parathion and dimethoate, respectively. When the strongly inhibition took place, 2-pyridinealdoxime methochloride (2-PAM) was successfully used to regenerated the enzyme activity. When the strongly inhibition took place, 2-pyridinealdoxime methochloride (2-PAM) was successfully used to regenerated the enzyme activity. |
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